With improvement in road maintenance (effects of snow removal and snow melting agent), the traveling speed range of a vehicle tends in general to increase recently. Thus, tires, such as winter tires for RV (Recreational Vehicle), are required to ensure during traveling in a certain traveling speed range (40 [km/h] or more) as well as traveling at a low speed.
To achieve such ice handling performance, a technology disclosed in Patent document 1 has been known as related to a conventional pneumatic tire. The conventional pneumatic tire includes symmetric profiles with respect to an equatorial plane. The profile on each side of the equatorial plane has at least three tread radii and a tread surface. At least two circumferential main grooves are formed on the tread surface. Part of the profile between the equatorial plane and the innermost circumferential main groove, part between adjacent circumferential main grooves, and part between the outermost circumferential main groove and a tread contact edge of a shoulder portion form arcs, respectively. On the profile are formed inflection points each on an intersection of adjacent arcs in the circumferential main groove. Every acute-angle side intersection angle between adjacent arcs at an inflection point is not less than 1 degree and not more than 3 degrees.
This structure ensures a contact area of even a wide tire and achieves uniform contact pressure, which improves tire ice handling performance.    Patent document 1: Japanese Patent Application Laid-open No. 2005-119481